MUSEUM OF COMPARATIVE ZOOLOGY. 311 



sometimes to the other, but when given to the true aura of Linne", Vieillot, 

 and Wilson, the atratus of Bartram and Wilson has been cited as a syno- 

 nyme, and the true atratus described under a new name. The name jota 

 has likewise been repeatedly applied to both species by different authors, 

 and in some cases even by the same author, as has been also the name 

 bra&iliensis. The description given by Linne in the twelfth edition of his 

 Systema Naturae, under V. aura, clearly refers to the V. aura of Wilson, of 

 which the V. jota of Molina and Gmelin are synonymes ; although some of 

 Linne's synonymes may refer to the C. atratus of modern writers. Bona- 

 parte, however, in both his Synopsis of the Birds of the United States and 

 in his Geographical and Comparative List, strangely applied the name jota 

 to the atratus of Wilson, in which he was for a time followed by other 

 writers. By those who have regarded the South American representatives 

 of C. aura as distinct from its North American ones, the name jota has 

 latterly been applied to the supposed distinct South American representa- 

 tive of the supposed true or northern C. aura. 



The distinctions between the so-called C. jota and C. aura seem, judg- 

 ing from the published accounts, to be by no means clear. Mr. Cassin, in 

 his report on the birds of Lieutenant Gilliss's Expedition, says the C jota 

 " is apparently, or so far as can be ascertained from prepared specimens, 

 a more slender bird, and loncjer in all its measurements. The last character 

 is particularly applicable to its wings."* In his Illustrations of the birds 

 of California and Texas, published the following year, he reverses this 

 statement, and says : " The South American species [C.jota] is the smaller," 

 and " is the more slender in all its members " ; and adds : " All the spe- 

 cimens that we have seen have been of a more uniform clear black color." 

 Having myself examined numerous specimens, both in Brazil and in Florida, 

 I find the difference in the average exceedingly slight, and nearly as stated 

 by Mr. Cassin in his later work ; that is, the Brazilian are slightly smaller, 

 and have the plumage appreciably darker. 



Bonaparte, in his Conspectus, gives the jota of Molina as being simply 

 smaller and with a shorter tail than aura of Linne. The differences are in- 

 deed very slight; they are, moreover, strictly in accordance with the well- 

 known general laws of variation between specimens of the same species from 

 northern and southern localities, and by no means indicate a diversity of 

 species. Because formerly not known to occur in some of the West India 

 Islands, it was at one time supposed by some that the habitats of the two 

 supposed species did not meet, or that there was a region in Central and 

 Northern South America where neither existed. As I have elsewhere 

 stated,f this is a mistake, both this species and the C. atratus ranging from 



* U. S Naval Astronomical Expedition, Vol. II, p. 173, 1855. 

 t Memoirs Bost. Soc. Nat. Hist., Vol. I, p. 500, 1S68. 



